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Prof. Chongdu Cho
Inha University (Department of Mechanical Engineering)

Basic Info


Research Keywords & Expertise

0 Solid mechanics, materials engineering, automotive engineering, medical engineering, tribology
0 Ceramic & Composite
0 FUEL CELL AND BATTERY
0 Finite Element Method and Simulation. Monte Carlo Simulation. Non Destructive Testing. Modeling. Random Numbers Generation.
0 composite materials, homogenization, micromechanics, solids mechanics

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Communication
Published: 07 June 2021 in Actuators
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A torque measurement method that combines the inverse magnetostrictive effect with twist angle measurement has been proposed in this paper. A Kalman filter and complementary filter are applied to significantly reduce the noises and errors in the proposed method. This new measurement block can detect the applied torque with an error of less than 1%. The proposed measurement method can be used in static and dynamic conditions.

ACS Style

Feng Xu; Vivek Dhimole; Chongdu Cho. Torque Measurement Technology by Using a Magnetostrictive Ring and Multiple Magnets. Actuators 2021, 10, 124 .

AMA Style

Feng Xu, Vivek Dhimole, Chongdu Cho. Torque Measurement Technology by Using a Magnetostrictive Ring and Multiple Magnets. Actuators. 2021; 10 (6):124.

Chicago/Turabian Style

Feng Xu; Vivek Dhimole; Chongdu Cho. 2021. "Torque Measurement Technology by Using a Magnetostrictive Ring and Multiple Magnets." Actuators 10, no. 6: 124.

Journal article
Published: 31 May 2021 in Materials
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The ankle joint of a powered ankle–foot orthosis (PAFO) is a prominent component, as it must withstand the dynamic loading conditions during its service time, while delivering all the functional requirements such as reducing the metabolic effort during walking, minimizing the stress on the user’s joint, and improving the gait stability of the impaired subjects. More often, the life of an AFO is limited by the performance of its joint; hence, a careful design consideration and material selection are required to increase the AFO’s service life. In the present work, a compact AFO joint was designed based on a worm gear mechanism with steel and brass counterparts due to the fact of its large torque transfer capability in a single stage, enabling a compact joint. Further, it provided an added advantage of self-locking due to the large friction that prevents backdrive, which is beneficial for drop-foot recovery. The design was verified using nonlinear finite element analysis for maximum torque situations at the ankle joint during normal walking. The results indicate stress levels within its design performance; however, it is recommended to select high-grade structural steel for the ankle shaft as the highest stresses in AFO were located on it.

ACS Style

Pruthvi Serrao; Vivek Dhimole; Chongdu Cho. Effect of Ankle Torque on the Ankle–Foot Orthosis Joint Design Sustainability. Materials 2021, 14, 2975 .

AMA Style

Pruthvi Serrao, Vivek Dhimole, Chongdu Cho. Effect of Ankle Torque on the Ankle–Foot Orthosis Joint Design Sustainability. Materials. 2021; 14 (11):2975.

Chicago/Turabian Style

Pruthvi Serrao; Vivek Dhimole; Chongdu Cho. 2021. "Effect of Ankle Torque on the Ankle–Foot Orthosis Joint Design Sustainability." Materials 14, no. 11: 2975.

Review
Published: 22 March 2021 in Polymers
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Fiber-reinforced composite structures are used in different applications due to their excellent strength to weight ratio. Due to cost and tool handling issues in conventional manufacturing processes, like resin transfer molding (RTM) and autoclave, vacuum-assisted resin transfer molding (VARTM) is the best choice among industries. VARTM is highly productive and cheap. However, the VARTM process produces complex, lightweight, and bulky structures, suitable for mass and cost-effective production, but the presence of voids and fiber misalignment in the final processed composite influences its strength. Voids are the primary defects, and they cannot be eliminated completely, so a design without considering void defects will entail unreliability. Many conventional failure theories were used for composite design but did not consider the effect of voids defects, thus creating misleading failure characteristics. Due to voids, stress and strain uncertainty affects failure mechanisms, such as microcrack, delamination, and fracture. That’s why a proper selection and understanding of failure theories is necessary. This review discusses previous conventional failure theories followed by work considering the void’s effect. Based on the review, a few prominent theories were suggested to estimate composite strength in the void scenario because they consider the effect of the voids through crack density, crack, or void modeling. These suggested theories were based on damage mechanics (discrete damage mechanics), fracture mechanics (virtual crack closure technique), and micromechanics (representative volume element). The suggested theories are well-established in finite element modeling (FEM), representing an effective time and money-saving tool in design strategy, with better early estimation to enhance current design practices’ effectiveness for composites. This paper gives an insight into choosing the failure theories for composites in the presence of voids, which are present in higher percentages in mass production and less-costly processes (VARTM).

ACS Style

Vivek Dhimole; Pruthvi Serrao; Chongdu Cho. Review and Suggestion of Failure Theories in Voids Scenario for VARTM Processed Composite Materials. Polymers 2021, 13, 969 .

AMA Style

Vivek Dhimole, Pruthvi Serrao, Chongdu Cho. Review and Suggestion of Failure Theories in Voids Scenario for VARTM Processed Composite Materials. Polymers. 2021; 13 (6):969.

Chicago/Turabian Style

Vivek Dhimole; Pruthvi Serrao; Chongdu Cho. 2021. "Review and Suggestion of Failure Theories in Voids Scenario for VARTM Processed Composite Materials." Polymers 13, no. 6: 969.

Journal article
Published: 01 March 2021 in Transaction of the Korean Society of Automotive Engineers
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ACS Style

Hyejin Bang; Yonghyun Ju; Hyeonnam Kim; Hyunshik Shin; Kyujong Park; Chongdu Cho. Development of Modeling Method for Computational Analysis of 3D Printing Model. Transaction of the Korean Society of Automotive Engineers 2021, 29, 257 -264.

AMA Style

Hyejin Bang, Yonghyun Ju, Hyeonnam Kim, Hyunshik Shin, Kyujong Park, Chongdu Cho. Development of Modeling Method for Computational Analysis of 3D Printing Model. Transaction of the Korean Society of Automotive Engineers. 2021; 29 (3):257-264.

Chicago/Turabian Style

Hyejin Bang; Yonghyun Ju; Hyeonnam Kim; Hyunshik Shin; Kyujong Park; Chongdu Cho. 2021. "Development of Modeling Method for Computational Analysis of 3D Printing Model." Transaction of the Korean Society of Automotive Engineers 29, no. 3: 257-264.

Journal article
Published: 27 November 2020 in Journal of Composites Science
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The mechanical properties of the material are essential to identify the material behavior of the structure. Predicting four-directional braided composites’ mechanical properties based on accurate modeling is an essential issue among researchers. In this research, the principle of minimum energy loss-based mechanics of structure genome was used for the two-step homogenization of three-dimensional (3D) four-directional braided composites. In the first step homogenization, the micro-scale model’s effective mechanical properties were decided by considering fibers and matrix; in the second step homogenization, the final effective mechanical properties of the meso-scale model were obtained by considering yarns and matrix. TexGen python script was implemented for accurate modeling of 3D four-directional braided cells with jamming effects. The current process sustainability was validated for 3D four-directional braided polymer matrix composites (PMCs) material by available finite element analysis (FEA) and experimental literature. The method is further extended for 3D four-directional braided ceramic matrix composites (CMCs) to confirm its versatility for standard composites. A commercial FEA was also performed on the meso-scale braided cell to validate the two-step homogenization results. This research explored fast and more accurate modeling and analysis techniques for 3D four-directional braided composites.

ACS Style

Vivek Kumar Dhimole; Yanqin Chen; Chongdu Cho. Modeling and Two-Step Homogenization of Aperiodic Heterogenous 3D Four-Directional Braided Composites. Journal of Composites Science 2020, 4, 179 .

AMA Style

Vivek Kumar Dhimole, Yanqin Chen, Chongdu Cho. Modeling and Two-Step Homogenization of Aperiodic Heterogenous 3D Four-Directional Braided Composites. Journal of Composites Science. 2020; 4 (4):179.

Chicago/Turabian Style

Vivek Kumar Dhimole; Yanqin Chen; Chongdu Cho. 2020. "Modeling and Two-Step Homogenization of Aperiodic Heterogenous 3D Four-Directional Braided Composites." Journal of Composites Science 4, no. 4: 179.

Journal article
Published: 25 July 2020 in Applied Sciences
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Estimating the parameters of sinusoidal signals is a fundamental problem in signal processing and in time-series analysis. Although various genetic algorithms and their hybrids have been introduced to the field, the problems pertaining to complex implementation, premature convergence, and accuracy are still unsolved. To overcome these drawbacks, an enhanced genetic algorithm (EGA) based on biological evolutionary and mathematical ecological theory is originally proposed in this study; wherein a prejudice-free selection mechanism, a two-step crossover (TSC), and an adaptive mutation strategy are designed to preserve population diversity and to maintain a synergy between convergence and search ability. In order to validate the performance, benchmark function-based studies are conducted, and the results are compared with that of the standard genetic algorithm (SGA), the particle swarm optimization (PSO), the cuckoo search (CS), and the cloud model-based genetic algorithm (CMGA). The results reveal that the proposed method outperforms the others in terms of accuracy, convergence speed, and robustness against noise. Finally, parameter estimations of real-life sinusoidal signals are performed, validating the superiority and effectiveness of the proposed method.

ACS Style

Chao Jiang; Pruthvi Serrao; Mingjie Liu; Chongdu Cho. An Enhanced Genetic Algorithm for Parameter Estimation of Sinusoidal Signals. Applied Sciences 2020, 10, 5110 .

AMA Style

Chao Jiang, Pruthvi Serrao, Mingjie Liu, Chongdu Cho. An Enhanced Genetic Algorithm for Parameter Estimation of Sinusoidal Signals. Applied Sciences. 2020; 10 (15):5110.

Chicago/Turabian Style

Chao Jiang; Pruthvi Serrao; Mingjie Liu; Chongdu Cho. 2020. "An Enhanced Genetic Algorithm for Parameter Estimation of Sinusoidal Signals." Applied Sciences 10, no. 15: 5110.

Journal article
Published: 27 December 2019 in Energies
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The electrical property of gas diffusion layers (GDLs) plays a significant role in influencing the overall performance of polymer electrolyte membrane fuel cells (PEMFCs). The electrical degradation performance of GDLs has not been reported sufficiently. Understanding the electrical degradation characteristics of GDLs is vital to better fuel cell performance, higher efficiency, and longer service time. This paper investigated the effective in-plane electrical resistivity of a commercial GDL by considering environmental and assembly conditions similar to those in use for the operation of PEMFCs. The effective in-plane electrical resistivity of the GDL, subjected to a series of freeze–thaw thermal cycles, was characterized to study its progressive electrical degradation with thermal cycles. Experimental results indicated that, under low compressive loads, the effective in-plane electrical resistivity of the commercial GDL showed weak anisotropy, and was greatly influenced by the transformation of carbon fiber connection in the porous layer. In particular, the thermal aging treatment on the GDL through the first 100 freeze–thaw cycles contributed a lot to its in-plane electrical degradation performance.

ACS Style

Yanqin Chen; Chao Jiang; Chongdu Cho. Characterization of Effective In-Plane Electrical Resistivity of a Gas Diffusion Layer in Polymer Electrolyte Membrane Fuel Cells through Freeze–Thaw Thermal Cycles. Energies 2019, 13, 145 .

AMA Style

Yanqin Chen, Chao Jiang, Chongdu Cho. Characterization of Effective In-Plane Electrical Resistivity of a Gas Diffusion Layer in Polymer Electrolyte Membrane Fuel Cells through Freeze–Thaw Thermal Cycles. Energies. 2019; 13 (1):145.

Chicago/Turabian Style

Yanqin Chen; Chao Jiang; Chongdu Cho. 2019. "Characterization of Effective In-Plane Electrical Resistivity of a Gas Diffusion Layer in Polymer Electrolyte Membrane Fuel Cells through Freeze–Thaw Thermal Cycles." Energies 13, no. 1: 145.

Journal article
Published: 03 October 2019 in Sensors
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In this paper, a three-dimensional finite element analysis (3D-FEA) model for shear horizontal surface acoustic wave (SH-SAW) torque sensors is presented. Torque sensors play a significant role in various fields to ensure a reliable torque transmission in drivelines. Featured with the advantages of high propagation velocity, large Q-value, and good power capacity, SH-SAW based torque sensors are promising but very few studies have been carried out. In order to develop a successful sensor, understanding the characteristics of SH-SAWs produced on piezoelectric substrates and torque sensing modes is indispensable. Therefore, in this study, we first investigated the effect on the generation of waves when different Y-cut quartz substrates are engaged. Thereafter, analyses and comparisons, regarding the effect on the polarized displacement, wave guidance, and wave mode, were conducted for different configurations of wave-guide layer thickness to wavelength ratios (hlayer/λ) and materials. Results show that Y-cut quartz at an angle close to 36° with a gold (Au) layer varying from hAu/λ = 0.02 to 0.03 thickness could be the most effective configuration for the excitation of SH-SAWs, compared to other combinations using platinum (Pt), titanium (Ti) and silicon dioxide (SiO2). Finally, based on the FEA SH-SAW torque sensor model configuring with a Y+36° quartz substrate and 0.025 λ-thick gold layer, the relationship between the applied torque and sensed voltage was examined, which shows a perfect linearity demonstrating the performance of the sensors.

ACS Style

Chao Jiang; Yanqin Chen; Chongdu Cho; Chen; Cho. A Three-Dimensional Finite Element Analysis Model for SH-SAW Torque Sensors. Sensors 2019, 19, 4290 .

AMA Style

Chao Jiang, Yanqin Chen, Chongdu Cho, Chen, Cho. A Three-Dimensional Finite Element Analysis Model for SH-SAW Torque Sensors. Sensors. 2019; 19 (19):4290.

Chicago/Turabian Style

Chao Jiang; Yanqin Chen; Chongdu Cho; Chen; Cho. 2019. "A Three-Dimensional Finite Element Analysis Model for SH-SAW Torque Sensors." Sensors 19, no. 19: 4290.

Original paper
Published: 19 May 2019 in Journal of Solid State Electrochemistry
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In this study, three-dimensional (3D) orthotropic mechanical properties of a commercial gas diffusion layer (GDL) are experimentally investigated. Although GDL is an important 3D structural membrane in proton electrolyte membrane fuel cells (PEMFCs), most papers have merely considered its in-plane linear isotropic characteristics due to the lack of 3D anisotropic mechanical performance investigation. In real operating PEMFCs, GDL is nonlinear orthotropic composite and its mechanical characteristics affect the overall performance of PEMFCs, seriously and directly. In this research, as considering GDL’s valid configuration in PEMFCs, mechanical tests such as compression test, tension test, and shear test are conducted to study its 3D mechanical behavior. Test results present that the GDL behaves in an orthotropic and nonlinear manner. In addition, microstructures of the GDL are observed through scanning electron microscope (SEM) images, to explain its different kinds of mechanical failure performance.

ACS Style

Yanqin Chen; Chao Jiang; Chongdu Cho. An experimental investigation of three-dimensional mechanical characteristics of gas diffusion layers in proton electrolyte membrane fuel cells. Journal of Solid State Electrochemistry 2019, 23, 2021 -2030.

AMA Style

Yanqin Chen, Chao Jiang, Chongdu Cho. An experimental investigation of three-dimensional mechanical characteristics of gas diffusion layers in proton electrolyte membrane fuel cells. Journal of Solid State Electrochemistry. 2019; 23 (7):2021-2030.

Chicago/Turabian Style

Yanqin Chen; Chao Jiang; Chongdu Cho. 2019. "An experimental investigation of three-dimensional mechanical characteristics of gas diffusion layers in proton electrolyte membrane fuel cells." Journal of Solid State Electrochemistry 23, no. 7: 2021-2030.

Journal article
Published: 06 March 2019 in Polymers
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In this paper, the mechanical degradation of a commercial gas diffusion layer subjected to repeated freeze–thaw thermal cycles is studied. In a fuel cell, the mechanical assembly state directly affects the performance of polymer electrolyte membrane fuel cells. Particularly, the gas diffusion layer repeatedly withstands the complex heat and humidity environmental conditions in which the temperature and humidity are always greatly changed. Studying the three-dimensional mechanical degradation of gas diffusion layers due to orthotropic properties is very useful in extending the lifetime and durability of fuel cells. To investigate this, we first established the standard freeze–thaw thermal cycle and studied the gas diffusion layer’s mechanical degradation performance with up to 400 repeated freeze–thaw thermal cycles. Furthermore, different types of failure in the gas diffusion layer caused by the repeated thermal aging treatment were observed using a scanning electron microscope, to explain the change in the mechanical deterioration. As a result, the different thermal failure plays different roles in the explanation of the gas diffusion layer’s mechanical degradation under different thermal cycles. In particular, the thermal failure that resulted from the first 100 thermal cycles has the greatest effect on the compressive and tensile performance, compared to the shear behavior.

ACS Style

Yanqin Chen; Chao Jiang; Chongdu Cho. Effects of Freeze–Thaw Thermal Cycles on the Mechanical Degradation of the Gas Diffusion Layer in Polymer Electrolyte Membrane Fuel Cells. Polymers 2019, 11, 428 .

AMA Style

Yanqin Chen, Chao Jiang, Chongdu Cho. Effects of Freeze–Thaw Thermal Cycles on the Mechanical Degradation of the Gas Diffusion Layer in Polymer Electrolyte Membrane Fuel Cells. Polymers. 2019; 11 (3):428.

Chicago/Turabian Style

Yanqin Chen; Chao Jiang; Chongdu Cho. 2019. "Effects of Freeze–Thaw Thermal Cycles on the Mechanical Degradation of the Gas Diffusion Layer in Polymer Electrolyte Membrane Fuel Cells." Polymers 11, no. 3: 428.

Article
Published: 08 February 2019 in International Journal of Automotive Technology
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A vehicle disk brake, which has cross drilled hole patterns on a frictional surface for improving cooling and braking performance, has propensity to cause crack problem under the harsh braking condition. In this study, the finite element analysis by using ABAQUS was adopted to investigate a cause of crack occurrence by the thermo-mechanical phenomenon around drilled hole patterns. As a remedy of the crack generation, the disk brake rotor with stress relieving and ferritic nitrocarburizing was prepared and tested on brake dynamometer in harsh condition. The test result was examined in terms of pad wear, the braking torque variation, the braking temperature changes, the crack initiation timing, and the crack propagation speed. As a test result, the disk after heat treatment showed 3.61 % higher average braking temperature than the disk without heat treatments, to suggest decreased heat dissipation performance, however, it also showed 14 % lower pad wear amount, and 0.1 % smaller braking torque variance than the disk without heat treatments, to stand for improved contact characteristics. Also, the heat treated brake rotor showed 51.3 % lower crack propagation rate which is considered as proper countermeasure of the fracture phenomenon at the edge of cross drilled hole.

ACS Style

Yunhwa Hong; Taeksu Jung; Chongdu Cho. Effect of Heat Treatment on Crack Propagation and Performance of Disk Brake with Cross Drilled Holes. International Journal of Automotive Technology 2019, 20, 177 -185.

AMA Style

Yunhwa Hong, Taeksu Jung, Chongdu Cho. Effect of Heat Treatment on Crack Propagation and Performance of Disk Brake with Cross Drilled Holes. International Journal of Automotive Technology. 2019; 20 (1):177-185.

Chicago/Turabian Style

Yunhwa Hong; Taeksu Jung; Chongdu Cho. 2019. "Effect of Heat Treatment on Crack Propagation and Performance of Disk Brake with Cross Drilled Holes." International Journal of Automotive Technology 20, no. 1: 177-185.

Conference paper
Published: 01 October 2018 in 2018 IEEE Sensors Applications Symposium (SAS)
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This paper presents a novel genetic algorithm (GA) for the parameter estimation of surface acoustic wave (SAW) sensor signal. Differently from conventional GA, a two-step crossover operation is proposed for better interchange between variables and individuals. Besides, to resolve the problem of premature convergence and to increase the population diversity, an adaptive mutation mechanism is integrated as well. In order to verify the performance of the proposed method, benchmark function based studies using traditional GA, particle swarm optimization (PSO), and our proposed algorithm are implemented. At the end, parameter estimations for simulated signal are carried out. All the results highlight the superiority of our algorithm.

ACS Style

Chao Jiang; Yanqin Chen; Chongdu Cho; Pruthvi Serrao. A Novel Genetic Algorithm Applied to Parameter Estimation of Passive Surface Acoustic Wave Torque Sensing Signal. 2018 IEEE Sensors Applications Symposium (SAS) 2018, 1 -4.

AMA Style

Chao Jiang, Yanqin Chen, Chongdu Cho, Pruthvi Serrao. A Novel Genetic Algorithm Applied to Parameter Estimation of Passive Surface Acoustic Wave Torque Sensing Signal. 2018 IEEE Sensors Applications Symposium (SAS). 2018; ():1-4.

Chicago/Turabian Style

Chao Jiang; Yanqin Chen; Chongdu Cho; Pruthvi Serrao. 2018. "A Novel Genetic Algorithm Applied to Parameter Estimation of Passive Surface Acoustic Wave Torque Sensing Signal." 2018 IEEE Sensors Applications Symposium (SAS) , no. : 1-4.

Journal article
Published: 26 September 2018 in IEEE Transactions on Magnetics
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For the design of magnetostrictive MEMS devices, finite-element modeling (FEM), the determination of the magnetostrictive coefficient, and application examples were examined in this paper. The magnetostrictive coefficients are usually calculated by measuring the bending deflection of the cantilever on which magnetostrictive materials are deposited. In most of the research on the magnetostrictive deposited substrate for the derivation of structural formulas, it is commonly assumed that the flexural rigidities of magnetostrictive materials are negligible because magnetostrictive films are much thinner than substrate materials. In this paper, the effect of magnetostrictive thin film's elastic energy on the magnetostrictive coefficient is investigated. A self-coded and developed finite-element program for magnetostrictive actuators is formulated, where magnetic properties are considered as nonlinear, and elastic properties are assumed as linear. As a result, it is potentially shown that magnetostrictive thin-film micropatterned actuators would be accommodated for targeted actuating behavior through an FEM capability for evaluation and selective micropatterning technique for fabrication.

ACS Style

Chongdu Cho; Yunhwa Hong; Chao Jiang; Yanqin Chen. Study of Dynamic Behavior of Magnetostrictively Patterned Flexible Micro-Wings. IEEE Transactions on Magnetics 2018, 55, 1 -4.

AMA Style

Chongdu Cho, Yunhwa Hong, Chao Jiang, Yanqin Chen. Study of Dynamic Behavior of Magnetostrictively Patterned Flexible Micro-Wings. IEEE Transactions on Magnetics. 2018; 55 (2):1-4.

Chicago/Turabian Style

Chongdu Cho; Yunhwa Hong; Chao Jiang; Yanqin Chen. 2018. "Study of Dynamic Behavior of Magnetostrictively Patterned Flexible Micro-Wings." IEEE Transactions on Magnetics 55, no. 2: 1-4.

Journal article
Published: 01 September 2018 in Polymers
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In this paper, a commercial gas diffusion layer is used, to quantitatively study the correlation between its compressive characteristics and its operating temperature. In polymer electrode membrane fuel cells, the gas diffusion layer plays a vital role in the membrane electrode assembly, over a wide range of operating temperatures. Therefore, understanding the thermo-mechanical performance of gas diffusion layers is crucial to design fuel cells. In this research, a series of compressive tests were conducted on a commercial gas diffusion layer, at three different temperatures. Additionally, a microscopical investigation was carried out with the help of a scanning electron microscope, to study the evolution and development of the microstructural damages in the gas diffusion layers which is caused by the thermo-mechanical load. From the obtained results, it could be concluded that the compressive stiffness of the commercial gas diffusion layer depends, to a great extent, on its operational temperature.

ACS Style

Yanqin Chen; Chao Jiang; Chongdu Cho. An Investigation of the Compressive Behavior of Polymer Electrode Membrane Fuel Cell's Gas Diffusion Layers under Different Temperatures. Polymers 2018, 10, 971 .

AMA Style

Yanqin Chen, Chao Jiang, Chongdu Cho. An Investigation of the Compressive Behavior of Polymer Electrode Membrane Fuel Cell's Gas Diffusion Layers under Different Temperatures. Polymers. 2018; 10 (9):971.

Chicago/Turabian Style

Yanqin Chen; Chao Jiang; Chongdu Cho. 2018. "An Investigation of the Compressive Behavior of Polymer Electrode Membrane Fuel Cell's Gas Diffusion Layers under Different Temperatures." Polymers 10, no. 9: 971.

Journal article
Published: 01 June 2018 in International Journal of Engineering and Technology
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ACS Style

BawoO Cha; Taeksu Jung; Yunhwa Hong; Sungsu Park; Cheongmin Kim; Younghoon Hong; Chongdu Cho. Design Optimization of Disc Brake for Reducing Squeal Noise by Frequency Sensitivity Analysis. International Journal of Engineering and Technology 2018, 10, 263 -268.

AMA Style

BawoO Cha, Taeksu Jung, Yunhwa Hong, Sungsu Park, Cheongmin Kim, Younghoon Hong, Chongdu Cho. Design Optimization of Disc Brake for Reducing Squeal Noise by Frequency Sensitivity Analysis. International Journal of Engineering and Technology. 2018; 10 (3):263-268.

Chicago/Turabian Style

BawoO Cha; Taeksu Jung; Yunhwa Hong; Sungsu Park; Cheongmin Kim; Younghoon Hong; Chongdu Cho. 2018. "Design Optimization of Disc Brake for Reducing Squeal Noise by Frequency Sensitivity Analysis." International Journal of Engineering and Technology 10, no. 3: 263-268.

Journal article
Published: 01 May 2018 in Journal of the Korean Society for Precision Engineering
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ACS Style

Chanyoung Park; Chongdu Cho. Effect of Protection Design Parameters on Mine Blast Impact Characteristics. Journal of the Korean Society for Precision Engineering 2018, 35, 521 -529.

AMA Style

Chanyoung Park, Chongdu Cho. Effect of Protection Design Parameters on Mine Blast Impact Characteristics. Journal of the Korean Society for Precision Engineering. 2018; 35 (5):521-529.

Chicago/Turabian Style

Chanyoung Park; Chongdu Cho. 2018. "Effect of Protection Design Parameters on Mine Blast Impact Characteristics." Journal of the Korean Society for Precision Engineering 35, no. 5: 521-529.

Article
Published: 27 February 2018 in International Journal of Automotive Technology
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Automotive brake noise has become a stubborn problem as automotive cars achieve higher driving torques, since that the increased torque induces the generation of severe noise dissipation during brake operation. Moreover, the global brake tuning market for achieving higher performance of the vehicle has expanded recently. The need to control the noise grows more in this connection. The tuning brake kits have employed cross-drilled and slotted machining pattern on the surface of the rotor. These designs have advantages to improve air ventilation, temperature control, and surface cleaning of brake pad. However, the effects of modal frequency by patterned rotor surfaces are rarely discussed, even if it is highly related with brake squeal phenomenon. Therefore, this study deals with the relationship between patterned surfaces and brake squeal through the numerical methods. The commercial software of a finite element analysis is employed for calculation by varying geometric design factors of each rotor pattern. As a result, the cross-drilled machining patterns are concluded to be an influential factor for in-plane mode frequency while the slotted patterns have more leverage for out-of-plane mode frequency.

ACS Style

Taeksu Jung; Yunhwa Hong; Sungsu Park; Cheongmin Kim; Younghoon Hong; Chongdu Cho. Numerical Study for Brake Squeal by Machining Patterns on Frictional Surface. International Journal of Automotive Technology 2018, 19, 281 -289.

AMA Style

Taeksu Jung, Yunhwa Hong, Sungsu Park, Cheongmin Kim, Younghoon Hong, Chongdu Cho. Numerical Study for Brake Squeal by Machining Patterns on Frictional Surface. International Journal of Automotive Technology. 2018; 19 (2):281-289.

Chicago/Turabian Style

Taeksu Jung; Yunhwa Hong; Sungsu Park; Cheongmin Kim; Younghoon Hong; Chongdu Cho. 2018. "Numerical Study for Brake Squeal by Machining Patterns on Frictional Surface." International Journal of Automotive Technology 19, no. 2: 281-289.

Journal article
Published: 01 January 2018 in Transaction of the Korean Society of Automotive Engineers
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ACS Style

Hyeonjin Kang; Taeksu Jung; Yunhwa Hong; Sungsu Park; Cheongmin Kim; Younghoon Hong; Chongdu Cho. Effect of Cross-drilled Hole Shape on Crack of Disk Brake Rotor. Transaction of the Korean Society of Automotive Engineers 2018, 26, 67 -76.

AMA Style

Hyeonjin Kang, Taeksu Jung, Yunhwa Hong, Sungsu Park, Cheongmin Kim, Younghoon Hong, Chongdu Cho. Effect of Cross-drilled Hole Shape on Crack of Disk Brake Rotor. Transaction of the Korean Society of Automotive Engineers. 2018; 26 (1):67-76.

Chicago/Turabian Style

Hyeonjin Kang; Taeksu Jung; Yunhwa Hong; Sungsu Park; Cheongmin Kim; Younghoon Hong; Chongdu Cho. 2018. "Effect of Cross-drilled Hole Shape on Crack of Disk Brake Rotor." Transaction of the Korean Society of Automotive Engineers 26, no. 1: 67-76.

Journal article
Published: 01 September 2017 in Transaction of the Korean Society of Automotive Engineers
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ACS Style

Yunhwa Hong; Taeksu Jung; Cheongmin Kim; Younghoon Hong; Chongdu Cho. An Experimental Study for Machined Patterns of Friction Surface on Two-pieces Disc Brake Rotor in Performance Aspect. Transaction of the Korean Society of Automotive Engineers 2017, 25, 581 -589.

AMA Style

Yunhwa Hong, Taeksu Jung, Cheongmin Kim, Younghoon Hong, Chongdu Cho. An Experimental Study for Machined Patterns of Friction Surface on Two-pieces Disc Brake Rotor in Performance Aspect. Transaction of the Korean Society of Automotive Engineers. 2017; 25 (5):581-589.

Chicago/Turabian Style

Yunhwa Hong; Taeksu Jung; Cheongmin Kim; Younghoon Hong; Chongdu Cho. 2017. "An Experimental Study for Machined Patterns of Friction Surface on Two-pieces Disc Brake Rotor in Performance Aspect." Transaction of the Korean Society of Automotive Engineers 25, no. 5: 581-589.

Article
Published: 19 August 2017 in Journal of Mechanical Science and Technology
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Composite materials are composed of multiple types of materials as reinforcement and matrix. Among them, CFRP (Carbon fiber reinforced polymer) is widely used materials in automotive and defense industry. Carbon fibers are used as a reinforcement, of which Young's modulus is in a prepreg form. In automotive industry, especially, high strain rate test is needed to measure dynamic properties, used in dynamic analysis like high inertia included simulation as a car crash. In this paper, a SHTB (Split Hopkinson tensile bar) machine is employed for estimating stress-strain curve under dynamic load condition on aluminum 6061 and CFRP. The strain rate range is about from 100 /s to 1000 /s and the number of prepreg layers of composite specimen is total eight plies which are stacked symmetrically to structure CFRP. As a result, stress / strain point data are obtained and used for simulation into stacked composites.

ACS Style

Hyejin Bang; Chongdu Cho. Failure behavior / characteristics of fabric reinforced polymer matrix composite and aluminum6061 on dynamic tensile loading. Journal of Mechanical Science and Technology 2017, 31, 3661 -3664.

AMA Style

Hyejin Bang, Chongdu Cho. Failure behavior / characteristics of fabric reinforced polymer matrix composite and aluminum6061 on dynamic tensile loading. Journal of Mechanical Science and Technology. 2017; 31 (8):3661-3664.

Chicago/Turabian Style

Hyejin Bang; Chongdu Cho. 2017. "Failure behavior / characteristics of fabric reinforced polymer matrix composite and aluminum6061 on dynamic tensile loading." Journal of Mechanical Science and Technology 31, no. 8: 3661-3664.